State of the art heating systems for buildings, though efficient in terms of energy, waste exergy and emit CO2. To overcome these issues, besides having an architecture that ensures symmetry of radiation and a low temperature heating emission system, a Heat Pump (HP) with the "right" heat source needs to be present. The supplied heat's quality will draw the line between a normal and a Low-Exergy and Zero Emission system. In this thesis, a new deep Coaxial Borehole Heat Exchanger (CBHE), without grout (BHE's back-filling material), with an insulated axial pipe and counter-flow regeneration was "brought to reality". Though only the theoretical aspects and simulation results are included here, it is worth mentioning that it is now commercially available.